1. Field of the Invention
The present invention relates to gold binding peptides and shape- and size-tunable synthesis of gold nanostructures.
2. Description of the Related Art
Recent advances in nanotechnology and heightened concern for the environmental impact of nanoscale materials requires the development of environmentally benign methods to synthesize nanostructures with controlled morphology and architecture. The size and shape of nanomaterials has a major influence on their physical and chemical properties and the ability to control these parameters remains a great technological challenge with important implications in nanoscale science and engineering1. Over the last 30 years2 several chemical synthesis methods have been developed to produce semiconducting and metallic nanostructures and several studies have demonstrated that their size-dependent properties are due to quantum confinement effect3. The shape and size of nanostructures are generally controlled by using hard templates or soft direct agents, including organic surfactants and polymers. The chemical synthesis of nanostructures, however, has several major drawbacks, including the use of toxic chemicals and extreme synthesis conditions involving high operating temperatures and pressure, and highly acidic or alkaline reaction conditions.
In contrast, several natural biological systems have been shown to produce inorganic materials under physiological conditions that have intricate nano-architectures and superior multi-functional properties. These biologically-synthesized materials include the zero- and three-dimensional nanostructures of magnetite4, metal sulfides5, selenium6, tellurium7, gold8, and silver9 and the one-dimensional nanostructures found in tellurium nanorods10 and arsenic sulfide nanotubes11. Relative to chemical routes, biological systems appear to be extremely adept at directing the synthesis and assembly of inorganic nanostructures to create hierarchical nanostructures at near ambient conditions, in environmentally compatible solutions, and utilizing eco-friendly reducing and capping agents12.
Engineered peptides that recognize inorganic surfaces have been shown to be useful for the assembly and synthesis of inorganic nanostructures13. For example, Brown et al. used gold binding polypeptides (GBP1), initially identified in a cell-surface display library, to synthesize nanometer thick platelets and nanoparticles of gold, suggesting the feasibility of synthesizing inorganic nanostructures using genetically engineered peptides14. Similarly, Xie et al. isolated a protein from the unicellular green alga Chlorella vulgars that formed nanometer thick gold platelets with high yield12. The size of platelets, which was defined as the longest possible width, was less than 0.1 mm15. Despite the variety of structures produced by biological systems, engineering applications frequently require uniformly precise nanomaterials with exacting and specific dimensional characteristics.
Throughout this application, various patents and publications are referenced and citations are provided in parentheses. The disclosure of these patents and publications in their entities are hereby incorporated by references into this application in order to more fully describe this invention and the state of the art to which this invention pertains.